1. Field of the Invention
The present invention relates to a machine tool with a tool change function, and more particularly to a machine tool with a tool change mechanism wherein a tool change arm is arranged to remove a protection cover member attached to the forward end of a spindle head for protection of a ring gear secured to the forward end of a tool spindle.
2. Discussion of the Background
In the case that a rotary tool holder of large diameter is supported in place by insertion into a tool receiving tapered bore in a standard tool spindle, the support rigidity of the tool holder becomes insufficient in heavy cutting. For this reason, it is required to couple the tool holder at its large diameter end with the forward end of the tool spindle by means of a gear coupling to thereby enhance the support rigidity of the tool holder. In this case, the gear coupling is composed of a pair of ring gears which are respectively secured to the forward end of the tool spindle and the large diameter end of the tol holder and arranged to be meshed with each other when the tool holder has been inserted into the tool spindle. For the purpose of protecting the ring gears from scraps of metal during operation of the tool spindle, it is desirable that a protection cover part is formed on the large diameter end of the tool holder to contain therein the ring gears and is replaced with a protection cover member removably attached to the spindle head to contain the ring gear on the tool spindle after removal of the tool holder.